Multiple-heater control



'Nov. 16 1926.

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. H. A. HANDS MULTIPLE HEATER CONTROL Filed June 17, 1926 4 Sheets-Sheet 2 To LoAD A Hand 7 Nov. 16 1926.

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H. A. HANDS MULTIPLE HEATER CONTROL Filed June 17, 1926 4 Sheets-Sheet 4 IMF.

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. Patented Nov. I 16, 1926.

UNITED STATES PATENT. OFFICE.

. I 7 s HOWARD A. HANDS, OF WATERTOWN, MASSACHUSETTS, ASSIGNOR TO HOOD RUBBER COMPANY, OF WATERTOWN, MASSACHUSETTS, A CORPORATION OF MASSACHU- SETTSV Application filed June 17,

My present invention relates to improved means for regulating the temperature ofa plurality of electric heaters and aims to .pro- I viderelatively simple, economical'and efli cient means whereby the temperature of said heaters may be regulated by a single control instrument operating on said heaters in sue cession.

The invention includes the novel construe readily understood. reference is made to the accompanying drawings in which: I

Figure 1 is a diagrammatic view; Fig. 2 is a sectional elevation. Fig. 3 is a detail view of the depressor bar and associated circuit closing parts.

Fig. 4 is an enlarged detail-view of the drum as seen in elevation.

' Fig. 5 is a detail plan view of the adjustable cam plates as viewed from above Fig. 4. Fig. 6 is a sectional detail on a larger scale to illustrate the cooperation of contact finger and drum strip.

Fig. 7 is a diagrammatic detail. Fig. 8 is EjfIOIlt elevation of a modified form of the invention embodied in apparatus for multiple control, parts being broken away and parts omitted for sake of illustration. Fig. 9 is a side elevation of the apparatus of Fig. 8 with parts in section. Fig. 10 is'an enlargeddetail section of one of the fixed discs for the distributor contacts, and

,Fig. 11 is a fragmental face view of the parts of Fig. 10. 1

Referring by reference characters to this drawing, Fig. 1, it is asspmed that there is a group of heaters, four being shown by way of example, and the position of whlch 5 is indicated conventionally at 76, 76, 76 and 76, and in which the temperatures are to be controlled automatically from a single control instrument, so designated on the drawing. 1 I Associated'with each heater is a thermocouple. these being designated',35, 35.

and 35 respectively, and while they are shown apart from the heaters for convenience in tracing the 'circuits,it will be un- I mourns-HEATER con'rnon 1926. Serial No. 116,652.

derstood that in practice they are incorporated in the heaters, or associated apparatus so as to be affected by the temperature thereof.

The thermo-co'uples are electrically connected to a. control instrument (so 'designated in the drawing) embodying a galva: nometer needle G (Figs. 2 and 3). having circuit closing means associated therewith and-adapted to be positioned by the movement,thereof, to cooperate with switch con- 35 tacts h, 0 and l of the. line connections marked H, C and L, and standing respec- ,tively for high, com'mon, and low. The ,cir-

cuit closing is effected by 'a depressor bar 100 operative throughout the range of movenent of the needle and which depressor bar may be operatedintermittently in anysuitable manner, but preferably by a solenoid. or

I magnet, as indicated at 74. -The needle G carries a projection g designed to engage one or the other of a pair of spring arms h and l electrically connected with the lines H and i L respectively and which arms respectively carry the contacts 7:. and Z which, when depressed, engage selectively the opposed contacts 0 which are both electrically connected to the common line C. a

A bridge I piece 101 of inverted wedge shape serves to deflect the needle to one side or the other (Fig. 3) if the depressor bar 35J should be, lowered when the needle is directly opposite the space between the ends of the spring arms k and Z It will be understood that if the temperature of the furnace is below the predetermined limit the galvanometer needle will be in suchposition that the action of the depressor bar will so control the circuits as t9 turnon the heat, while. if above a fipredetermined limit, the heat will, be cut '0 this operation broadly being well understood by those skilled in the art.

This isefi'ected in the present instance by electrically connecting the H and L'contacts with the conductors 15 and 16 respectively of the power line (here indicated for, example as a volt A C line, Fig. 1) and the C contact to relays or contactors comprising solenoids 11, 11, 11"or 11, one for each furnace, each of which when energized closes switches or contacts 12, 12*, 12 or 12, and also the. control switches or contacts 13, 13', 13". or 13, see Fig. 7.

The heaters' are connected to the power line throu h the main contacts 12, 12, 12", and 12, w ile in series with each set of control contacts 13, 13 13 and 13, is a resistor 14 of predetermined value.

In order to makethe one control instrument eflective to control a plurality of I heaters, I provide circuit controlling means which I prefer to construct in the shape of a cylindrical drum 36 of insulating material and of suitable dimensions, driven at slow ,speed through suitable connections by a pletely around the drum, and four others- 39,. 40, 41, and 42, each covering only onequarter of the periphery, all in separate paths. Set #2 consists likewise of a conductor strip 43 extending completely around the drum, and four others 44, each covering perhaps one-twentieth of the periphery, These last four 44, are all in the same path. Set #3 is similar to set #1, having the strip 20 all around with four other contacts, 22, 45, 46 and 47, all in different paths, but each of the last four, 22, v45, 46 and 47, covers only say one-thirtieth of the periphery. To .engage with these twelve strips are twelve flexible contact fingers 19, 23 and 48. to 57 inclusive, mounted on the framework of the instrument. Contacts 39 to 42 inclusive are permanently connected to contact 38 by connectors 5 8 to 61 inclusive; 44 to 43 by connectors 62, and 22, 45, 46 and 47 by connectors 21, 63, 64 and 65, respectively.

Starting with everything cold, snapn switch 26 is turned on. Motor 37 starts to rotate drum 36. Contacts 48, 53 and 19 are 1n contact with the full length strip contacts 38, 43 and 20 respectively, and finger con-- tact 49 is in contact with strip contact 39. This completes a circuit through 35, 66, 49, 39, 58, 38, 48, 70, through the galvanometer of the control instrument, and wire 71 back to the thermocouple. As the thermocouple is cold, no current will flow in thiscircuit and the galvanometer needle will remain at the lower end of the scale. Afternva short interval of time, the turning of the drum 36 brlngs contacts 44 and 54 together, completing a circuit from line 15 through 72, 53, 43, 62, 44, 54, 73, solenoid 74, and wire 75, back to line 16. Energizing the solenoid lowers the depressor bar and causes the low contacts ,L and C. (under present coni1t10n) to momentarily close. A further sli ht turn of drum'36 bringscontacts 22 an 23 together, completing a circuit from line 16 through 17, L, C, 18, 19, 20, 21,

22, 23, 24, 11, 25, 2c, and 27 to line 15. This 34, 29 and 30to line 16. 'Thesimultaneous closing of contacts 13 completes a circuit from line 16 through 30, 29, 14, 13 and 28 to the solenoid 11, a pathin parallel with the circuit through the instrument contacts L and C. Heater 76 is now on and thermocouple 35, associated with it, begins to heat up. w

7 Further rotation of the drum 'opens contact connections between 49 and 39, 54 and 44, 23 and 22, allowing the depressor-bar to rise, and opening the circuit through L and C. Solenoid ll still remains energized, however, through the parallel path through contacts 13, and the power stays on heater 76.

Coincident with the breaking of these circuits, another circuit is made through finger contact 50 and strip contact 40, completing a circuit through thermocouple 35 and the galvanometer of the control instrument. The cycle described above is gone through again, until at its completion heater 7 6* is on the line. In like manner 7 6 and 76 are connected to the line as drum 36 continues to revolve.

After one complete rotation of the drum,

thermocouple 35 is again connected to the alvanometer through contacts 39 and 49. ts temperature has supposedly risen by this time, but it may or may not be as high as the temperature for which the control instrument 1s set. If it is not, nothing changes. The depressorbar drops, finds the pointer still on the low side of the setting, closing contacts L and C, which simply complete acircuit in parallel with one already existing through contacts 13..

Closing con- This condition exists for all couples and heaters until the temperature at one'of the couples rises abovethe desired point.' Assume that this condition exists when contact 39 reaches contact 49 on. a certain-rotation. The current through the circuit then. due to the excess temperature of couple 35, causes the galvanometer needle to go beyond the temperature setting. Upon the closing of the contacts 44 and 54, the depressorbar finds the needle on the high. side and consequently closes the high contacts H and C. This sets the stage for the completion of a circuit from'line 15 through 31, H. G?, 18, 19, 2o, 21, 22, 23, 24, 28, 13,14. 29 and 30 to line 16 as soon as the contacts 22 and 23 are closed. This shorts out solenoid 11,contacts 12 and. 13 open, and. both heater,

7 6 circuit and the control circuit through 13 are opened. The temperature of heater 76 then begins to fall.

Thus the various cycles go on, with a heater circuit being opened or closed according to whether its associated couple indicates a temperature higher or lower than that desired, and thus the temperature of all four heaters are kept within a reasonable range of the temperature desired.

It is frequently desirable that different heaters shall be capable of being set to operate at different temperatures-and I have accordingly provided means by which any given heater may be set for any desired temperature without otherwise affecting the action of the control instrument. To this end the H, C and L contacts are carried by a post 101 having its lower end secured to the outer end of a swinging arm 102, fast on the upper end of a shaft 103 in axial alignment with the axis of the galvanometer needle. This shaft carries an arm 104 provided at its free end with a roller 104 adapted to coact with a series of contact plates 105 adjustably secured to a disc 106 fixedly attached to the upper end of the drum 36 or its shaft. Each of these plates 105 has an outer edge concentric with the axis of the drum and *it is made radially adjustable of the carrying plate 106 by means such as slots and clamp screws as shown in Fig. 6. A spring 107 tends to rotate the shaft 103 to keep the roller 106lin contact with the peripheries of plates 105. There being one plate for each heater it 'will be seen that the position of the corres onding plate, to wit, the amount of its racial adjustment, will determine the temperature of its respective heater due to the angular adjustment of arm 102 carrying the control contacts.

The invention is capable of use for the control of a very large number of heaters in which event I prefer to modify the distributor mechanism as shown for example in Figures 8 to ll'inclusive.

In this I have shown the distributor con-- tacts corresponding to sets 1 and 3 of the first form described above as carried by fixed discs 110, 110, the cooperating contacts or brushes (corresponding to 19 Fig."

5) being carried by arms lll fast on a shaft 11:2 driven by suitable gearing. from a motor 113 through the intermediary of a suitable speed transformer 114. In this form I have shown the depressor bar as mechanically operated (instead of electrically) this being effected by a cam disc 115 co-operating with and actuating the plunger rods 116 which in turn actuates the depressor bar in a manner similar to that disclosed in Fig. 2. Cam disc 115 is fast on a chain and sprocket gearing from shaft 112. The adjustable temperature controlling discs shaft 117 driven by.

(corresponding to 105 of the first form) are shown at 118 carried on the periphery of a drum 119 fast on a shaft 120 driven by'chain and sprocket gearing from shaft 117. V

In this embodiment I have shown the drums as provided with plates or cams for the control of temperature of fifteen heaters. The plates are secured to the periphery of the drum by clamp screws 118 passing through elongated openings in the plates and adjusting screws 118 serve for accurate adjustment when the clamp screws are loosened.

In Figures 8 to 11 the circuits are omitted for simplification of illustration as the manner of providing these would beobvious to one skilled, in the art in view of the disclosure in connection with Figs. 1 to 7.

As indicated in Fig. 8 the shafts 112, 117 and 120 may be of such length as to provide for the control of a' plurality of groups of heaters.

By this arrangement a very large number of heaters may be controlled as to temperature from a single control station.

Having thus described my invention, what I claim is:

1. In anautomatic temperature regulator for a plurality of electric heaters, a plurality of thermo electric elements associ-. ated with said heaters, a plurality of circuit controllers for regulating the current supplied'to said heaters, a single control instrument adapted to be influenced by one or another of said thermo electric elements. I

and a common distributor with switches .and connections whereby the single control instrument is placed in operative relation with one or another of said thermo electric, elements and with the corresponding circuit controllers. I

2. In an automatic temperature regulator for a plurality of electric heaters, a plurality of thermo electric elements associated" with said heaters, a plurality of circuit con trollers for regulating the current supplied to said heaters, a single control instrument adapted to be influenced by one or another of said thermo electric elements, means associated with said control instrument for determining the temperature of any given heater, and a common distributor with switches and connections whereby the single control instrument is placed in opera-- tive relation with one or another of said thermo electric elements and with the corresponding circuit controllers.

3.111 a control system,the combination of a plurality of heaters, a single electrical instrument adapted to trolled by the temperature of said heaters, and comprising a pointer and means for controlling said heaters including two eectric circuits having movable terminals separate from but dependent upon said-pointer,

be successively conlli) means, for periodically causing said pointer to selectively actuate said terminals to close said circuits, and means for automatically moving said terminals to a predetermined position relative to any particular heater.

4. In a control system, a plurality of electric heaters, a plurality of thermoelectric elements associated with said heaters, a plurality of circuit. controllers for regulating the current supplied to said heaters, a single tive relation with said thermo electric ele-' ments and the corresponding circuit closers.

and a member moving in unisonwith said distributor and having individually ad ustable parts corresponding in number to said heaters, and means whereby said individual parts control the position of said terminals.

5. In a control system, a plurality of electric heaters, a plurality of thermo electric elements associated with said heaters, a plurality of circuit controllersfor regulating the current supplied to said heaters, a single control instrument adapted to be influenced by one or another of said ,thermo electric elements and comprising a pointer, and means for governing the action of said circuit closers including two electric circuits having movable terminals spaced from but dependent upon said pointer to selectively actuate said terminals, means for periodical-1y actuating said pointer to closeone or the other of said circuits, a continuously driven common distributor with switches and connections whereby the single control instrument is placed successively in operative relation with said thermo electric elements and the corresponding circuit closers, said terminals being mounted for bodily movement in a path concentric to the axis of said pointer, and means for bodily moving said terminals comprising a rotary member having adjustable contact elements corresponding in number to the number of heaters, and a cooperating contact member having operative connection with said terminals. s

6. An automatic temperature regu ator according to claim *1 in which the distributor comprises a fixed disc or, disc's carrying one set of contacts and the cooperating contacts are carried by aswing arm fast on a motor driven shaft.

7. An automatic temperature regulator according to claim 1 in which the distributor comprises a fixed disc or discs carrying one set of contacts and the cooperating contacts are carried by a swing arm fast on a motor driven shaft, and the depressor bar of the control instrument is operated by a rotary cam carried by a shaft driven from the aforesaid shaft.

8. An automatic temperature regulator according to claim 1 in which the distributor comprises a fixed disc or discs carrying one' set of contacts and the cooperating contacts; are carried by a swing arm fast on a motor driven shaft, and the depressor bar of the control instrument is operated by a rotary cam carried by a shaft driven from the aforesaid shaft, and in which the terminals of the control elements carried on the periphery of adrum mounted on a shaft driven from the shaft carrying the depressor bar actuating cam.

9. In an automatic temperature regulator for a plurality of electric heaters, a plurality of thermo-electric e ements associated with said heaters, a plurality of circuit .coutrollers for regulating the current supplied to said heaters. a single control instrument adapted to be influenced by one or another of said thermo-electric elements, a common distributor with switches and connections whereby the single control instrument is placed in operative relation with one or another of said thermo-electric elements and with the corresponding circuit controllers, and means whereby the action of each thermo-electric element on the control instrumentmay be varied relative to and independent of the action of each and every other thermo-electric element, and a variable resistence included in the circuit of each thermo-electric element.

10. In a control system, the combination ofa plurality of heaters, a single electrical instrument connected .to be successively controlled by the temperature of said heaters and comprising a pointer and means for controlling said heaters including two electric circuits having movable terminals separate from but dependent upon said pointer, means for periodically causing said pointer to selectively actuate said terminals to close said circuits, and means for varying the control exercised by each heater over said single electrical instrument independent of the control exercised by the other heaters.

In testimony whereof, I afltix my signature.

HOWARD A. HANDS. 

